The seizure took place following a court order after the Iranian EB patients filed a complaint against the United States. 

The Iranian EB patients filed a complaint against the US due to the sanctions imposed on Iran which prevent the import of the drugs needed by them. 

After the court order was issued, the US oil cargo was seized from the ADVANTAGE SWEET oil tanker in the Persian Gulf. 

The Iranian EB patients had lodged a complaint against the United States at the legal court of international relations (branch 55) of Tehran after the sanctions imposed by the Western states, above all the US, prevented the sale of special medical bandages and pharmaceuticals by a Swedish company to Iran and caused serious physical and mental damages to the patients suffering from EB, a group of rare, inherited skin disorders that cause the skin to become very fragile and blister easily.

After legal proceedings and efforts by the attorney of the case, the Iranian court issued a warrant for the confiscation of the American oil cargo carried by Advantage Sweet tanker in the Persian Gulf.

The oil tanker was seized afterwards.